Improvement in rotary valves



2 Sheets--Sheet 1.

A. LAWRENCE.

Improvement in Rotary-Valves.

Patented May 7,1872.

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2 Sheets-Sheet 2.

A. LAWRENCE. Improvement in Rotary-Valves. N0.126,402. nted May7,1872.

Y'w fl k 4 UNITED STATES PATENT OFFICE.

ALVIN 'LAVVRENCE, OF LOWELL, MASSACHUSETTS.

IMPROVEMENT IN ROTARV VALVES.

Specification forming part of Letters Patent l\'o. 126,402, dated May 7, 1872. e

To all whom it may concern:

' Be it known that I, ALVIN LAWRENCE, of Lowell, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Valves for Steam-Engines, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing making part of this specification, in which- Figure 1 represents a plan of the valve and the adjustable cut-off as applied to the steamchest, the cover thereof having been removed to show the position of the parts. Fig. 2 represents a plan of the valve-seat and the interior of the steam-chest after the valve has been removed, showing both the steam and the exhaust ports. Fig. 3 represents a cross-section of the steam-chest outside of the end of the valve. Fig. 4 represents the under side of the steamchest on the line of the curved outer surface of the steam-cylinder, showing the construction and arrangement of the steam and exhaustports and passages. Fig. 5 represents a modification of the valve, the Us and lands being straight instead of spiral, as in Fig. 1. Fig. 6 is an end elevation of Fig.5. Figs. 7 andS represent each a cross-section of the valve, the seat, the steamchest, and the cylinder, respectively,on the lines A B and U D of Fig. 1, showing in 7 the valve in position for the steam to be working expansively, this having been cut oii' at a preceding point in the rotary action of the valve, and in 8 showing the, exhaust closed and the valve nearly ready to admit steam to the other end of the cylinder. Figs. 9, 10, and 11 represent difi'erent elevations of the adjustable cut-off slide detached, and enlarged to twice the size of the same parts seen in Figs. 1 and 3. Fig. 12 represents a plan of a portion of the interior of the steam-cylinder opposite or covered by the steam-chest, showing the admission-ports at each end of the cylinder, and also the steam and exhaust passages in dotted lines. Fig. 13 represents a central longitudinal section of Fig. 12. Figs. 14 and 15 represent certain modifications embodying my invention.

This invention has for its object to furnish a simple, cheap, and very eificient valve, that will cut off the admission of steam, or the steam admitted to the cylinder, at any required point of the stroke, without interfering in the least degree with the time of opening and closing the exhaust-ports, which is the principal difficulty attending the use of the common slidevalve; and this invention has for its object to furnish an adjustable cut-off, in combination with the valve and steam-admission ports, whereby the time of cutting off steam may be changed or varied to suit the occasion-that is to say, when the working-engine is cutting off steam at half-stroke, by a suitable movement of the adjustable cut-01f slide or gauge the valve will cut off steam to the cylinder earlier or later, or at one-quarter stroke, or at three-eighths stroke, or at any other point of the stroke desired-all of which gives the con nected engine the capacity to work steam more expansively than the slide-valve.

In connection with theimproved valve, the seating of the valve and the steanradmission and exhaust-ports and passages are constructed with special reference to the construction of the valve, and so that each part is adapted to operate in connection with the other or others, as hereinafter described.

To construct, apply, and use my said improvements, the steam-cylinder is made in the usual way, and provided with steam-ports a at each end thereof, and to the side of this steam-cylinder,and covering the ports a, I apply the steam-c-hest A, suitably fitted and packed, and secured to the cylinder or cast in one therewith. That side of the steam-chest next to the cylinder contains the admissionports b and steam-passages (1, leading from the ports b to the ports a in the ends of the cylinder, and also exhaust-ports h, and an exhaust steam-wa y, K, leading to the pipe or outlet m at one side of the chest. Above the ports b and h the semicircular valve-seat is formed in the side of the chest, and the cylindrical valve B is closely fitted to the seating above the ports.

The cylindrical valve is constructed with sunken Us or cavities D, and bands or full cylindrical surfaces 0 between the full central portion and the full ends or heads E, and the Ds are intended to be about twice the width of the lands, and the distance from the cut-ofi c to the steam-ports b on the valve-seat less than the width of each D, and this last-named seat-space is widened or narrowed by a movable cut-ofl' slide, F, arranged within the steamchest and close to the surface of the valve, so that by moving the adjustable cut-oft slide the inclined surfaces or cut-off edges 0 will either narrow or widen the seat-space between the cut-off and the admission-ports, and cause the valve to cut ott' earlier or later, or at a different point of the stroke; or if preferred the cut-off may be made permanent when constructing the steam-chest, and so as to cut ofl' the steam at any given point of the stroke; or

such cut-off may be composed of one or a se-' ries of plates, 0, as shown in Fig. 8, and the time of cutting ofi' steam regulated by removing one or more of said plates, or by reapplying one or more of them.

When this valve is constructed, as shown in Fig. 1, with the Ds and lands spirally, this brings the Ds at one end of the valve sufiiciently forward or ahead of those at the opposite end to allow the admission of steam alternately to opposite ports I) and to opposite ends of the cylinder, and also to allow the steam to exhaust from one end of the cylinder while taking steam at the other end.

The same efl'ect or result is produced by a valve constructed with straight parallel Ds and lands or faces 0, as shown in Fig. 5; but in this modification of the valve the Ds in one end of the valve must be opposite or in line with the faces 0 at the opposite end, so that when such last-named valve rotates the opposite Ds and faces will alternately expose and cover the opposite admission and exhaust ports, and allow the admission and exhaust of steam alternately at opposite ends of the cylinder, as with the spiral D-valve, before described, the valve shown in Fig. 5 being considered an obvious substitute forthat shown in the other figures.

\Vhen the straight D-valve is used the cutofl' may be a fixed or permanent cut-ofl' or removable plates 0, which may be made to slide up to or back from the face of the valve either singly or severally, and thus narrow or widen the seat-space between the cut-oti point and the admission-ports b, and thereby regulate or determine the time orthe periods of cuttin g off steam at any desired point of the stroke of the piston.

In constructing my improved valve I sometimes divide it transversely at the center-say on the line 4 4-and run a spindle through the tn 0 parts, or a hollow spindle through one part and a solid spindle through the other part, and this allows the two divided parts to be adjusted relatively with each other, so as to bring the Ds and lands in one part any distance forward of those in the other part; or the two parts may be operated separately by separate spindles.

Rotary motion is imparted to the valve by a ratchet, or gear, or pulley, P, on the stem S, which is made steam-tight by an ordinary stufting-box, G. The cut-oft slide 1* may be operated to adjust it by a rod, g, passing through the end of the steam-chest. The ports b and passages d, and end-ports a, constitute the steam-admission ports, and the ports h, and passage K, and outlet m constitute the exhaustports, or the operative steam-exhausting outlets.

I claim as my invention- 1. In combination with the valve and its seat, and ports constructed as described, a fixed or adjustable cut-01f, 0, arranged as and for the purpose set forth.

2. A cylindrical or circular valve, constructed as described, with Ds or cavities, and lands or faces, and operating in connection with a corresponding seat having a cut-01f and ports to admit and exhaust steam by the continuous or intermittent rotary motion of the valve,

as set forth.

ALVIN LAWRENCE.

Witnesses:

JOHN E. CRANE, D. HALL RICE. 

